_IO_file_underflow_mmap read call for atime

[Ulrich Drepper]

Roland McGrath wrote:

> And it doesn't update atime on read faults as well?  That is permissible
> behavior, but not very helpful.  It makes atime pretty useless if it's
> possible there are mmap readers.  There could be a process that opened the
> file and mmap'd it a year ago, and then later something does a write so
> mtime > atime; then if the first process reads the new data, atime remains
> unchanged and sometime contemplating mtime vs atime would conclude that the
> new data has not been read by anyone.

I don't know enough about the implementation.  I only know that the read 
is needed if mmap happened at fopen time.  You can talk to the kernel 
people.

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